Method and machine for narrowing tubular articles

ABSTRACT

This method and machine for narrowing tubular articles comprise the steps of and machine for fitting the tubular article on a blank holder which is provided with a core slidably mounted on the holder and a plurality of die-forming radial sectors pivoted about horizontal pivot pins and shaped so as to be adapted to produce with their inner contours the desired narrowing of the article.

United States Patet 1191 1 1 6 111. 1 Get. 9, 1973 METHOD AND MACHINE FOR 188,643 I 3/1877 Jordan et a1. 72/193 NARROWING TUBULAR ARTICLES 396,361 1/1889 M 685,417 /1901 W1ll1ams or: Pierre q, m y, France 1,625,340 4/1927 Thomas 72/189 [73] Assignee: Agence Nationale de Valorisation de 1: 3;? erche Nanny-museum Primary ExaminerLowell A. Larson Attorney- Waters, Roditi, Schwartz & Nisscn [22] Filed: Mar. 19, 11971 [21] Appl. No.: 126,203

[57] ABSTRACT [30] Foreign Application Priority Data Mar. 20, 1970 France 7011359 This method and machine for narrowing tubular arti cles comprise the steps of and machine for fitting the [52] U.S. Cl. 72/402, 72/224 tubular article on a blank holder which is provided [51] Int. Cl B2111 51/02 with a core slidably mounted on the holder and a plu- [58] Field of Search 72/82, 189, 193, rality of die-forming radial sectors pivoted about hori- 72/212, 213, 224, 399, 402 zontal pivot pins and shaped so as to be adapted to produce with their inner contours the desired narrow- [56] References Cited ing of the article.

UNITED STATES PATENTS 16,630 2/1857 Platt..... ..Q 72/189 5 Claims, 7 Drawing Figures m f i m I 1 t l jiifi f 5 I H 1a 3 Z/ 1. l 9 IQ i I III I I t, :1 I :1 I l 1 18 8 V 17 r 17 18 19 l 49 51 4 a1 a2 26 v I 3 3o '1,- 1,

K 9 29 2 M I 1 I 1 1 T33 1Q 33 1 27 a]: e 1, 2a 3a 2 51 31 36 PATENTEUUBT 1 1 SHEET 1 [1F 3 PATENTED 9 975 SHEET 3 BF 3 METHOD AND MACHINE FOR NARROWING TUBULAR ARTICLES FIELD OF THE INVENTION The present invention relates to methods of and chines for narrowing tubular articles.

DESCRIPTION OF THE PRIOR ART piece from a given initial diameter to a smaller diameter, but by driving the bottom of the piece through and into a die by means of a punch. In contrast thereto, with the method of this invention the same result is achieved without applying any stress to the workpiece bottom and without producing frictional slippage in order to avoid scoring the workpiece surface and/or tearing the material, which is a major drawback encountered in most stamping operations utilizing a conventional dieand-punch unit.

In essence, according to this invention the shaping sectors act in unison as a power assembly which, in lieu of the conventional stamping die, reduces the diameter of the tubular article by driving and rolling the metal thereof on the inner core.

The present invention is directed to various imrpovements in or relating to t the methods and machines known in the prior art, these improvements concerning primarily l. The synchronous operation of the core and radial sectors,

2. The operation of the sectors,

3. The simplification of the machine and the obtaining of a greater versatility in its operation as an independent unit.

Regarding the synchronous operation of the movements performed by the core and radial sectors, it was noted that according to hitherto known arrangements as the operativeends of said sectors described a greater are than the driven point thereof manufactures tended to reserve a substantial amount of lost-motion in the tie-rods in order to avoid any interference with the core during the core movement.

SUMMARY OF THE INVENTION The present invention provides a device which, by reproducing by means of links the movement, of the sectors, determines a similar movement-of thecore while permitting a certain free motion thereof in that this movement is not completely identical with that imparted to the workpiece by the sectors.

In the prior art construction the sectors reacted above-mentioned frictional contact by replacing the conventional plain bearings with knee-action devices provided with needle-bearings which are specially designed for this purpose.

To the same end, the conventional shoes are replaced by links also mounted on needle bearings for transmitting the stress to the sectors, and the links are so mounted in relation to the control plate that the sectors are returned in a positive manner to their initial positions.

Finally, the machine has been considerably simplified by utilizing a single table or bed for supporting the hydraulic control cylinders and the blank support thereof.

Furthermore, a greater versatility of the machine is due to the fact that the length of the sector arc is no longer limited by the thrust shoes, so that longer workpieces can be safely narrowed. Moreover, by positively actuating the core it is possible, by a suitable off-setting of the sector movements, to narrow workpieces throughout their length, whether these workpieces comprise along the whole or part of their length portions not of revolution, without modifying the metal thickness nor construcing the base as is currently done, and which results in abrasion or scoring due to severe frictional contact, as in conventional stamping works.

According to another feature of the invention, in the case of extremely thin metal workpieces likely to develop the so-called banana buckling effect in the workpiece section adjacent to the neck, the machine comprises a pneumatic air cushion consisting of a diaphragm adapted to during the narrowing operation, support the normally unsupported portion of the workpiece in order to counteract this buckling effect. This diaphragm is reduced by deflation or the application of vacuum during the return movement, so as to permit this movement.

Moreover, it is pointed out that the sector inclination utilized in-certain instances in the prior art is obviated the present invention, due to the improved guiding ac tion exerted on the lins,since the sectors are disposed in planes extending parallel to the axis of the machine. Moreover, their operative portions may be constructed to be detachable.

BRIEF DESCRIPTION OF THE DRAWINGS In order to afford a clearer understanding of this invention an embodiment thereof will now be described with reference to the accompanying drawing, in which:

FIGS. 1 and 2 are elevational views partly in section, showing the machine before its actuation and at the end of the operative stroke or cycle, before the return stroke and the workpiece ejection;

FIGS. 3 and 4 are fragmentary elevational view partly in section, before the operation and during the initial phase of the operation, respectively, showing the pneumatic means for supporting the neck of the workpiece;

FIG. 5 is a fragmentary top plan view of FIGS. 3 and 4; and

FIGS. 6 and 7 are detail views showing the assembling of the links and sectors.

DESCRIPTION OF THE PREFERRED EMBODIMENT According to the assembling and machine of this invention the sectors 1 are pivoted to members 2 secured to a support 3, these members 2 supporting a core 15 constituting the inner race of needle bearings of which the outer races are formed in said sectors.

Each assembly thus constituted is secured laterally by means of a screw 14 or rivet locking flanges 16 to the aforesaid cores 15. However, the assembling of members 2 and sectors 1 by means of the male portion of flanges 16 which acts as a tenon both in sector 1 and in members 2 permits the desired rotation by means of a suitable lost-motion or play, and a hollow channel formed in the flanges 16 receives segments adapted to hold the needles 12a assembled as shown in FIG. 7.

The aforesaid sectors 1 are pivotally connected to links 5 assembled in pairs by riveting another core 13 constituting the inner race, a bore formed in each sector constituting the outer race. The needles l2 housed therein are retained laterally by the links themselves (FIG. 6).

The other end of each link 5 is mounted in the same manner so as to constitute together with a support 11, a needle pivot. These supports 11 are secured to a plate 6 by means of circular segments 7 and rigidly connected by radial keys with this plate.

The plate 6 is fitted onto rods 8 which impart thereto an alternating rectilinear motion generated by hydraulic cylinders 18 having their pistons 17 connected rigidly with the rods 8.

These cylinders are secured to the under side of a table 9 which assembled by means of screws and nuts 10 to four frame structure elements 35 consisting of sheet plate elements 35 and which are cut by using a gas torch. The sheet plate elements 35 are assembled symmetrically in pairs and are rigidly assembled with the support 3 at their respective upper portions (FIG. 1).

The table 9 has also rigidly fitted in its center the support 21 of a blank holder 20, in which a core 24 is slidably fitted. This core 24 is coupled to a central tie-rod 25 extending downwards through plate 9.

A support 27 carrying a pair of transverse lateral trunnions 28 is disposed on the central tie-rod 25 between two sets of nuts 26; and links 29 which are pivoted to the frame structure at 30 are adapted to transmit an upward thrust to the support 27. These links 29 are actuated by the afore-said cylinders 18 through depending piston rods 31 which are provided with blocks 32 carrying transverse lateral trunnions 41 adapted to engage elongated holes formed in the links 29, as shown. The reactions of the force-components acting at 41 are absorbed by guide sockets 33 which are secured to gussest 34 in turn rigidly secured the frame structure, of which the lower portions are interconnected by a bottom plate 36.

The core 24 may be equipped (FIGS. 3 and 4) with a diaphragm 38 which is automatically expandable by pneumatic inflation at a predetermined time, this diagram consisting of a rubber bladder or the like fitted onto the core in a fluid-tight manner and in a predetermined axial position by means of the tapered portion of a head 37 screwed to the core 24. The folded end of this diaphragm is clamped in a fluid-tight manner to the core 24 by means of the tapered portion of a ring 39 which is screwed to the core. A duct 40 is provided for directing compressed air into the bladder.

The operative end la of sectors 1 may be detachable so as to accomodate different dimensions for the narrowing operation contemplated, without the need for replacing the complete sectors, or for reconditioning the part in case of failure (FIG. 7).

Depending upon whether the workpiece is to be narrowed along one fraction or the whole of its length, the above-described machine operates as follows 1. Partial narrowing Assuming that the machine is in its inoperative condition (FIG. 1), the workpiece 23 is inserted onto the blank holder so as to cap the latter down until the lower edge of the workpiece engages an abutment ring 22.

The operator actuates an electromagnet valve so as to supply oil from a pump (not shown) to the cylinders 18 via an inlet port 19. The movement of pistons 17 which are rigidly connected with plate 6 causes the latter to rise together with the links 29 controlling the support 27, which is fastened to be rigid with the tie-rod 25 and core 24.

The sectors 1 which are urged by links 5 now begin to describe a circular arc and commence to narrow the workpiece 23 while causing the latter to move between the sectors and the blank holder 20.

It is noted that the arcuate contour, concentric with the sectors 1, which constitutes the generatrix of the blank holder forms or provides along its useful length only the passage which is necessary for the metal, thereby preventing the building up of corrugations or folds.

The sectors 1 continue to drive the workpiece 23 upwards and the diameter of the workpiece approaches the final dimensions, while its wall thickness has gradually increased.

When the operative portions of the sectors and the workpiece are aligned, with respect to the horizontal plane containing their centers or pivot axes, the core 24, also attaining this position, takes over the task previously accomplished by the blank holder 20 for supporting the rolling work performed on the workpiece in order to restore its thickness to the initial value.

It is noted that the sectors 1 are, at that time, without any lateral play and thus act as a complete, solid ring.

Upon completion of the shaping of the workpiece 23 (FIG. 2), the oil supply is directed to the other inlet port 19a. The pistons are driven downwardly and carry along, through the rods 8 and 31, the elements attached to these pistons, i.e. the sectors 1 and core 24 on which the workpiece is fitted, so that all these elements move downwardly.

When the free edge of workpiece 23 engages the upper portion of blank holder 20 the latter of which is fixed, the ejection phase begins, the workpiece remaining stationary while the core 24 continues its downwards stroke. At the end of this stroke the workpiece is released.

Finally, in the case of a thin workpiece formed of relatively moderately ductile metal, of which only one portion is to be narrowed, the workpiece portion closely adjacent to the portion to be reduced in diameter so as to form the neck may tend to buckle and display what is commonly referred to as a banana effect. In order to avoid this drawback the core may comprise the arrangement illustrated in FIG. 3, i.e. an air bladder consisting of a diaphragm 38. In this case the blank holder 20 is slightly truncated in order to afford a quicker action.

The initial phase of the reducing operation enables the core to emerge from the blank holder upon which the diaphragm 38, having just received compressed air,

of the narrowing operation, the air contained in the dia phragm 38 is released, so that the diaphragm resumes its initial shape, and eventually the return stroke takes place so as to eject the workpiece 23.

2. Narrowing a blank throughout its length In this case the bottom of the workpiece must abut against the blank holder and accomodate its shape by adhering to its arcuate contour. When starting the operation the sectors 1 move without carrying along the workpiece, due to the shape of this workpiece, in order to present their efficient working positions. The core 24 which is driven with the necessary time-lag will not push the workpiece 23 so as to insert it into the rolling unit constituted by the sectors 1.

The same process as in the preceding case will now complete the piece without having to pull it from the bottom, so that a workpiece can be narrowed completely commencing from the bottom of its skirt at a considerable coefficient of reduction.

Finally, it will be readily understood by those skilled with the field of this invention that the latter should not be construed as being exactly limited by the specific forms of embodiment or the methods described and illustrated herein, since it also includes all modifications and variations that may occur to those skilled in the art. Thus, workpieces comprising longitudinal notches or teeth, such as pinions, pulleys for cogged belts, etc. may be shaped with this method.

What we claim as new is:

l. A method of narrowing tubular workpieces while regulating their thickness, comprising the steps of fitting said tubular workpiece on a blank holder, a support positioned on a plate, said holder being fastened to an end ofsaid support, a core slidably mounted for movement through said holder, operating hydraulic cylinder and piston actuators for moving said workpiece and core assembly upwards between a plurality of die-forming radial sectors centered to said assembly and pivoted about horizontal pivot pins disposed in a common plan perpendicular to the axis of said assembly, said sectors being shaped to produce with their inner contours the desired narrowing of said workpiece when said actuators are supplied with fluid under pressure, said actuators have piston rods connected, respectively, to a plate having said support for said blank holder acting as a guide post thereof, and an equivalent number of links connected to the inner ends of said sectors, a large quantity of said sectors being radially spaced each being of short thickness and having a constant contour and constant section over the entire working area thereof, and to linkage means adjustably connected to a central rod coupled to said core through the plate supporting said blank holder and through said blank holder whereby said upward movement of said assembly is attended by the desired narrowing, by rolling action, of said workpiece by said sectors operating in synchronism with said core.

2. Method as set forth in claim 1, comprising the step of supplying compressed air to an inflatable bladder fitted to said core and adapted, by bearing against the inner wall of the workpiece, to support same during the narrowing operation.

3. Method as set forth in claim 1, comprising the steps of providing a lost motion between the core and blank holder in order to produce the ejection of the narrowed workpiece at the end of the operation.

4. A machine for narrowing tubular workpieces, while regulating their thickness, which comprises a single bed plate, a plurality of upstanding gas-cut plates constituting a frame structure supporting at a first level a fixed plate supporting a pair of depending cylinder and piston hydraulic actuators perpendicular thereto and having their pistons provided with rods extending up and downwards from said actuators, and at a second level overlying said fixed plate a ring-shaped support to which a plurality of radial sectors are pivoted through needle bearings, the inner, free ends of said sectors being shaped to perform a predetermined narrowing of a tubular blank centrally of said sectors, said fixed plate being rigid with a central support carrying a fixed blank holder in which a core is slidably mounted and adapted to receive the workpiece and to eject same when an axial relative movement is produced between said holder and core, a plurality of vertical links disposed in radial and coplanar relationship to said sectors and connected to the free inner ends thereof through needle bearings, said core being connected through a concentric rod extending through said central support and fixed plate and provided with adjustable connecting means to linkage means diposed beneath said fixed plate, whereby the upward operative stroke of said actuator pistons isattended by the narrowing of said workpiece by the synchronized rolling action exerted by said sectors and the downward inoperative return stroke of said pistons is attended by ejection of said narrowed workpiece.

ing the narrowing operation. 

1. A method of narrowing tubular workpieces while regulating their thickness, comprising the steps of fitting said tubular workpiece on a blank holder, a support positioned on a plate, said holder being fastened to an end of said support, a core slidably mounted for movement through Said holder, operating hydraulic cylinder and piston actuators for moving said workpiece and core assembly upwards between a plurality of die-forming radial sectors centered to said assembly and pivoted about horizontal pivot pins disposed in a common plan perpendicular to the axis of said assembly, said sectors being shaped to produce with their inner contours the desired narrowing of said workpiece when said actuators are supplied with fluid under pressure, said actuators have piston rods connected, respectively, to a plate having said support for said blank holder acting as a guide post thereof, and an equivalent number of links connected to the inner ends of said sectors, a large quantity of said sectors being radially spaced each being of short thickness and having a constant contour and constant section over the entire working area thereof, and to linkage means adjustably connected to a central rod coupled to said core through the plate supporting said blank holder and through said blank holder whereby said upward movement of said assembly is attended by the desired narrowing, by rolling action, of said workpiece by said sectors operating in synchronism with said core.
 2. Method as set forth in claim 1, comprising the step of supplying compressed air to an inflatable bladder fitted to said core and adapted, by bearing against the inner wall of the workpiece, to support same during the narrowing operation.
 3. Method as set forth in claim 1, comprising the steps of providing a lost motion between the core and blank holder in order to produce the ejection of the narrowed workpiece at the end of the operation.
 4. A machine for narrowing tubular workpieces, while regulating their thickness, which comprises a single bed plate, a plurality of upstanding gas-cut plates constituting a frame structure supporting at a first level a fixed plate supporting a pair of depending cylinder and piston hydraulic actuators perpendicular thereto and having their pistons provided with rods extending up and downwards from said actuators, and at a second level overlying said fixed plate a ring-shaped support to which a plurality of radial sectors are pivoted through needle bearings, the inner, free ends of said sectors being shaped to perform a predetermined narrowing of a tubular blank centrally of said sectors, said fixed plate being rigid with a central support carrying a fixed blank holder in which a core is slidably mounted and adapted to receive the workpiece and to eject same when an axial relative movement is produced between said holder and core, a plurality of vertical links disposed in radial and coplanar relationship to said sectors and connected to the free inner ends thereof through needle bearings, said core being connected through a concentric rod extending through said central support and fixed plate and provided with adjustable connecting means to linkage means disposed beneath said fixed plate, whereby the upward operative stroke of said actuator pistons is attended by the narrowing of said workpiece by the synchronized rolling action exerted by said sectors and the downward inoperative return stroke of said pistons is attended by ejection of said narrowed workpiece.
 5. A machine as set forth in claim 4, wherein said core comprises an inflatable bladder acting as a diaphragm for supporting the wall of said workpiece during the narrowing operation. 